1. Field of the Invention
The present invention relates to an optical data recording and reproducing apparatus, or more particularly, to an optical disk drive unit whose components can be assembled easily.
2. Description of the Related Art
In recent years, the processing abilities and processing speeds of personal computers have improved and the storage capacities thereof, for programs including an operating system and application software and for data, have increased. Under these circumstances, storage devices are required to be compact and cost low. Besides, there is an increasing demand for a larger storage capacity and a higher reading/writing speed.
Optical disk drive units, or in other words, optical data recording and reproducing apparatuses, have come to prevail as storage devices capable of meeting the requirements for compact design, low cost, large storage capacity, and a high reading/writing speed. The optical disk drive unit converges laser light on an optical disk and records information on the optical disk by utilizing the heat generated. Moreover, optical disks compatible with this type of optical disk drive unit are generally encapsulated in a cartridge. When an optical disk is inserted into the optical disk drive unit for the purpose of use, a shutter of the cartridge is opened. The hub of the optical disk is engaged with a turntable of a spindle motor mounted in the optical disk drive unit, whereby the optical disk is rotated. Along with the spread of the optical disk drive unit using an optical disk cartridge, ease in assembling components, stability and reliability in performance, and reduction in cost are in great demand these days.
The structures and mechanisms described below are adopted in a conventional optical disk drive unit designed to accept an optical disk cartridge.
(1) A structure for mounting a load/ejection mechanism, of which components need not be assembled highly precisely, on a reading/writing mechanism whose components must be assembled highly precisely.
(2) A structure for linking the reading/writing mechanism and load/ejection mechanism with a flexible cable or cable. Herein, a printed wiring board having a circuit for controlling the mechanisms mounted thereon is included independently of the reading/writing mechanism and load/ejection mechanism.
(3) A structure for detecting the internal temperature of a housing using a temperature sensor and setting the conditions for reading or writing data. The structure is used to detect the temperature of a medium, which is an optical disk, affecting writing of data onto an optical disk.
(4) A structure for detecting the home position of a carriage, wherein a sensor for detecting the home position of the carriage included in a movable optical assembly is incorporated in the housing.
(5) A structure for accurately aligning a center yoke with a side yoke constituting each of several magnetic circuits included in the movable optical assembly.
(6) A mechanism for adjusting the slope of an objective so that the optical axis of the objective mounted on the carriage will lie perpendicular to the surface of the turntable of the spindle motor.
(7) A structure for positioning a stationary optical assembly independently of the reading/writing mechanism, load/ejection mechanism, and printed wiring board. The stationary optical assembly includes a source of laser light incident on an optical disk, a light detector, and a light passage which guides laser light to an optical disk, splits light reflected from an optical disk and guides the split reflected light to the light detector.
(8) A structure having a switch for judging the type of cartridge, or specifically, whether a cartridge is an optical disk cartridge having a magneto-optical disk on which data can be written, or whether a cartridge is a cleaning cartridge.
The present applicant has filed an application for an optical disk drive unit having the foregoing structures and it has been granted a patent as U.S. Pat. No. 5,694,314 (comparable to Japanese Unexamined Patent Publication No. 7-210878).
However, the optical disk drive unit has drawbacks to be overcome as described below.
(1) The load/ejection mechanism is attached to the reading/writing mechanism that is produced highly precisely at a preceding step. There is a possibility that the precision in assembling attained at the preceding step may be impaired to be insufficient due to the assembling work performed at the succeeding step. Moreover, the reading/writing mechanism and load/ejection mechanism cannot be handled mutually independently. This leads to time-consuming assembling and repairing steps.
(2) Since the reading/writing mechanism, load/ejection mechanism, and printed wiring board are connected by the flexible cable or cable, the flexible cable or cable has a plurality of nodes. This leads to time-consuming assembling work. A decrease in the number of nodes is required.
(3) The temperature sensor is not located near an optical disk. The temperature of a medium that is the optical disk is calculated from a temperature value detected by the sensor. The precision in the detected medium temperature is therefore insufficient. The conditions for reading and writing data must be set more precisely.
(4) The home position sensor for detecting the home position of the carriage included in the movable optical assembly is incorporated independently in the housing. A dedicated cable and connector are therefore needed for transmitting a detection signal output from the sensor to the printed wiring board. This leads to a higher cost.
(5) Conventionally, the center yoke and side yoke are aligned with each other using a pin and notch. The outer dimensions of the magnetic circuit must be increased in order to ensure a large area for the joint between the yokes.
(6) The slope of the objective mounted on the carriage is adjusted so that the optical axis of the objective becomes perpendicular to the surface of an optical disk. Since the adjusted part is a movable part, the adjustment is hard to do. Moreover, since the structure required for adjustment is included in the carriage, the carriage becomes heavy.
(7) Since the stationary optical assembly is included independently of the reading/writing mechanism, it is necessary to align the optical axis of the stationary optical assembly with the optical axis of the reading/writing mechanism. Thus, assembling efficiency is poor.
(8) A switch for identifying a cleaning cartridge is also needed.
Accordingly, an object of the present invention is to provide an optical data recording and reproducing apparatus, that is an optical disk drive unit, capable of meeting several requirements. The requirements include: (1) simplification of assembling and repairing steps; (2) decrease in the number of junctions between a mechanism and a printed-circuit board; (3) improvement of precision in detecting the temperature of a medium that is an optical disk; (4) reduction in cost; (5) compactness in the design of a magnetic circuit; (6) reduction in the weight of a carriage; (7) improvement of efficiency in assembling components of a stationary optical assembly; and (8) decrease in the number of switches.
The constituent features of the present invention for accomplishing the above object will be described below.
According to the first aspect of the present invention, there is provided an optical data recording and reproducing apparatus for optically recording or reproducing information on or from a commutative medium. The optical data recording and reproducing apparatus consists of a driving mechanism and a printed wiring board. The driving mechanism assists in loading a cartridge, in which a commutative medium is incorporated, into a main unit, drives the commutative medium, and reads or writes data from or onto the commutative medium. A control circuit for driving and controlling the driving mechanism is mounted on the printed wiring board. The driving mechanism can be divided into a load/ejection mechanism and a reading/writing mechanism. The load/ejection mechanism is a united body consisting of at least a sensor for identifying a cartridge, an ejection motor for ejecting the cartridge from the main unit, and a bias magnet assembly. The reading/writing mechanism is a united body consisting of at least a movable optical assembly and a stationary optical assembly. The movable optical assembly includes a spindle motor for rotating a commutative medium and a carriage for optically accessing the commutative medium. The stationary optical assembly is optically connected to the movable optical assembly.
According to the first aspect, the load/ejection mechanism and reading/writing mechanism can be separated from each other and can therefore be produced at mutually independent assembling steps. This leads to a simplified production line. The reading/writing mechanism is merely attached to the load/ejection mechanism at a succeeding step. Therefore a part adjusted at a preceding step is not disordered.
According to the second aspect of the present invention, based on the first aspect thereof, a signal line used to drive a carriage included in the reading/writing mechanism and a signal line used to drive the spindle motor are integrated into a flexible cable or cable. The flexible cable or cable is then linked to the printed wiring board.
According to the second aspect, only one electrical interface is interposed between the reading/writing mechanism and printed wiring board. This contributes to an improvement in assembling efficiency and a decrease in the number of parts.
According to the third aspect of the present invention, based on the first aspect, a temperature sensor for detecting the internal temperature of the apparatus is included in a spindle motor assembly of the reading/writing mechanism.
According to the third aspect, the temperature sensor is mounted on a seating of the spindle motor included in the spindle motor assembly. This leads to saving of spaces and decrease in the number of parts. Moreover, the spindle motor is located near an optical disk. The temperature of a medium, essential in controlling the conditions for recording, can be detected accurately.
According to the fourth aspect of the present invention, based on the first aspect, a position sensor for detecting the home position of the carriage included in the movable optical assembly is mounted on the spindle motor assembly included in the reading/writing mechanism.
According to the fourth aspect, the home position sensor is mounted on the seating of the spindle motor included in the spindle motor assembly. This leads to saving of space and a decrease in the number of parts.
According to the fifth aspect of the present invention, based on the first aspect, magnetic circuits are used to drive the carriage, which is included in the movable optical assembly, in directions along tracks on a commutative medium within the reading/writing mechanism. Each magnetic circuit is composed of a center yoke and a side yoke having a permanent magnet attached thereto. The center yoke is fixed to the base of the reading/writing mechanism using screws. The portions of the side yoke that join the center yoke each have a concave part in which the head of the screw is stowed. The side yoke is aligned with the center yoke using the heads of the screws.
According to the fifth aspect, the heads of the screws are used to align the yokes with each other. Consequently, a contact area at which the yokes are in contact with each other can be made large without the necessity of increasing the outer dimension of each magnetic circuit. Consequently, saturation in the magnetic circuit can be prevented.
According to the sixth aspect of the present invention, based on the first aspect, a mechanism is included for fixing the spindle motor to the base of the reading/writing mechanism at three points. The fixing mechanism consists of three legs, screw holes, a reference plane, and three pairs of pressurizing members and screws having the same sizes. The three legs are jutted out equidistantly from the seating of the spindle motor, and each have a screw passage hole bored therein. The screw holes are bored in the base of the reading/writing mechanism to be opposed to the screw passage holes of the legs. The reference plane is formed around one of the screw holes bored in the base. One of the three legs is higher by the height of the pressurizing members than the others. The one leg is regarded as a reference point in a height direction, matched with the reference plane, and then mounted on the base while being pressurized with the pressurizing member and screw. The other two legs are screwed to the base with the pressurizing members between the legs and base. The magnitude of tightening the two screws is adjusted, whereby the slope of the turntable of the spindle motor can be adjusted in the course of manufacturing the optical data recording and reproducing apparatus.
According to the seventh aspect of the present invention, based on the sixth aspect, the screw passage holes bored in the three legs are such that a triangle drawn with the centers of the screw passage holes as vertices thereof is an isosceles triangle. The isosceles triangle has the center of the screw passage hole in the reference plane as a vertex thereof.
According to the eighth aspect of the present invention, based on the sixth aspect, the screw passage holes bored in the three legs are such that a triangle drawn with the centers of the screw passage holes as vertices is an equilateral triangle. The equilateral triangle has the center of rotation of the spindle motor as the center of gravity thereof and has the center of the screw passage hole in the reference plane as a vertex thereof.
According to the sixth to eighth aspects of the present invention, the slope of the objective mounted on the carriage relative to an optical disk can be adjusted during mounting of the spindle motor on the reading/writing mechanism. This results in a simplified manufacturing process.
According to the ninth aspect of the present invention, based on the first aspect, the stationary optical assembly of the reading/writing mechanism consists of a laser diode, a collimator lens, a beam splitter, a Wollaston prism, a condenser lens, and a sensor. The base of the reading/writing mechanism is dented in the form of letter L. The laser diode, collimator lens, and beam splitter are placed in a dent extending in a moving direction in which the carriage moves. The Wollaston prism, condenser lens, and sensor are placed in a dent formed in a direction orthogonal to the moving direction of the carriage.
According to the tenth aspect of the present invention, based on the ninth embodiment, the base is post-machined in order to form planes, of which dimensions are accurate, in the L-shaped dent. The collimator lens and condenser lens are placed on the planes whose dimensions are accurate.
According to the ninth and tenth aspects of the present invention, the stationary optical assembly can be highly precisely united with the reading/writing mechanism. The optical axes of the reading/writing mechanism and stationary optical assembly can be adjusted during construction of the reading/writing mechanism. This leads to improvement in assembling efficiency.
According to the eleventh aspect of the present invention, based on the first aspect, the cartridge type judgment sensor is not included in the load/ejection mechanism. Instead, a judging means is included in the control circuit on the printed wiring board for controlling the number of rotations of the spindle motor in the reading/writing mechanism. The judging means judges a completion time at which activation of the spindle motor is completed after a cartridge is inserted into the load/ejection mechanism. When the spindle motor activation completion time is too short, the judging means recognizes that the inserted cartridge is a cleaning cartridge.
According to the eleventh aspect, the switch for identifying the cleaning cartridge is unnecessary. This leads to a saving of space and a decrease in the number of parts.